Distance-measuring instrument.



H. JACOB.

DISTANCE MEASURING INSTRUMENT.

APPLICATION TILED 1120.9, 1910.

Patented July 8, 1913.

UNITED STATES.

PATENT QF lQ-E HEINRICH J ACOB, 0F STEGLI'IZ, NEAR BERLIN, GERMANY,ASSIGNOR TO THE M 0F :OPIISCHE ANSTALT C. P. GOERZ AaKT BERLIN, GERMANY.

DISTANCE-MEASURING I NSTBUKENT.

menace,

To all-whom'ifi may concern a Beit known that I, HEINRICH Jaoon, acitizen ofth German Empiraand res'ident of Steglitz,-i,ie arBerli n,Germany, have invented certain newand useful Im 'rovements' m tlfollowing a specification. a Y This invention-relates to so-calledbaseline distance'measuringinstruments of, the class wherein the dividinline ofthe image field is substantially para lei; with the plane of themeasuringtriangle, and the-object of the invention is so to constructthe Instrument that it is adapted-.botnfor measuring the distance ofobjects. based on the ground, and rising more or=less to apo'intorcrest}, and for measuring the distance. of object such as air-ships,which are suspendedin the atmosphere and the mass of which is gener allyso distributed that the. most strikin ly apparent portions thereof aredownwar' 1y. d1rected. I

Experience has shown, that for accurate training on objects withupwardly directed oints, the distance measuring instruments bestadaptedare those having prismsystems arranged so that images appearing below.

the. dividing line are 11 right, whereas images above the dividing lineare inverted.

This arrangement enables pointed promontories of the objects to beeasily brought into coincidence with each other. In the case of objectshaving their most cons icuous parts directed downward it is, there ore,desirable to arrange the prism system so that the image below the dividiline is inverted, and the image .above sai line upright, so that thesaid conspicuous arts, recurring in both images, can be broug t intocoincidence with each other.

According. to the present invention both the conditions set forth aremet by providing the distance measuring instrument with an ocular devicewhich enables thereflectivc surface roducing the dividin line to beviewed rom oppositesides, 1n directions which make an an le with eachother, so that according to w ether the said reflective surface isviewed from one side or the other, it has a reversing eflect on thelower or on the upper image. The ocular device may either comprise twooculars placed at an angle to each other, as shown in Figure 1 of thedrawing, or a single, rotatable ocular Specification mm Patent.Application flled Deeem ber 9. 910. e -gin No. 596,521.

istance-Measuring Instruments, of which Patented J l 8,1913.

y be provided as ehowii in-ri teof the drawing. In the case of-aninstrument; with a straight'line of view, with the-uprightimage belowthedividing line and the mvertedimage above same, the fact-that reversaljof the relative positions ofthe images is tainableby alteringthe. angle of view at the ocular affords the possibility of facilitatingthe observation of air-ships and the like towardwhich the instrument isdirected. The invention is, illustrated in the annexed drawings, inwhich I l f Fig. 1 is an axial section of the ocular system' of adistance-measuring instrument having two ocula s placed at anangl'e.Figs. 2 and 3 represent double images of an airship, diflering according'to whether the view measuring instrument.

In Fig. 1 of the drawing, the oculars are marked a and b respectively,it being. assurned thatxthe ocular a gives a rectilinear view, theocular axis being, therefore, substantially parallel to the plane of themeasuring triangle. The ocular. system comprises in a known manner acombination of two crossed prisms c and d, the prism 11 being roofshaped. These two crossed prisms c and d serve to transmit the rays fromthe ends of the base line toa composite ocular prism consisting of arhombohedral prism e and a right angled equilateral prism f: At part ofthe junction between the'two risms e and f there is a coating 9', which1s reflective on both sides, and the termination of which forms thedividing line It. V

In the general view represented in Fig. 5, i i are pentahedral prisms atthe ends of the-base, which deflect the entering rays into-the directionof the lon 'tudinal axis of the instrument. m is an a justableindicator, and n is the scale for taking readings.

When a distant object is viewed through the ocular a in a right line,the image appearing above the dividing line b is re flected by thecoating g and then appears reversed, if originally upright. On viewingthrough the ocular b, the image above the dividing line appearsasreflected by the prism surface in front of the reflective surmNoEsnLsHaFr, o;F FRIEDENAU, .NEAn

is taken through one or the otheroculai.

face 9. That is to say, it is upright, whereas r the image below thedividing line is inverted, by deflection by the double sided re flectorg, contrary to what is the case on viewing through the ocular a, whensaid lower image'is outside the influence of the reflective surface g.

Fig. 2 shows an air-ship viewed through ocular b, and Fig. 3, the sameobject viewed through ocular a. Comparison of Figs. 2 and 3 will showthat more accurate training of the instrument is in this case obtainableby viewing through ocular b.

The modified construction of the ocular system illustrated in Fig. 4shows only one single ocular 0 carried by a rotatable casing p; saidcasing pis mounted on a second cylinder g provided with a slit 1-allowing angular displacement of the ocular 0 on cylinder 9. The ocularprisms are of the same kind as those shown in Fig. 1, and therefore aredesignated again 0, d, e, f,

the reflective coating is a ain designated 9 and its edge h. The two'inds of observation correspond in this instance to the position of theocular shown in full lines on the one hand and to the position shown indotted lines on the other.

What I claim is:

1. In a distance-measurin instrument provided with means for pro ucingimages device provided 'with a two sided reflective surface and twooeulars placed at an angle to each other, each of said oculars arran edin front of one side of said two sided re eetive surface.

3. In a distance-measuring instrument provided with means for producingimages of distant objects on o posite sides of an image dividing linesubstantially parallel with the plane of the measuring triangle, anocular device comprising a prism system with a double sided reflectinglayer inserted in the path of the rays passing through the instrument,said reflecting layer having an edge vforming the dividing line in theimage field, and being so arranged that the rays coming from distantobjects and impinging on one side of the double sided reflecting layerare reflected in a direction substantially coincident with the plane ofthe measuring trian Ie, the rays 1m inging on the other side 0 saidreflecting ayer being reflected in a direction crossing the plane of themeasuring triangle, the rays reflected from each of the sides of thedouble sided reflecting layers forming an image on one side of the imagedividing line, the image formed by the first mentioned rays cooperatingwith an image on the other side of the dividing line so that an invertedimage is formed above and an upright image below the image dividingline, whereas the image formed by the rays reflected by the other sideof the reflecting layer cooperates with an image on the other side ofthe reflecting layer so that an upright image is seen above and aninverted image below the dividing line.

In testimony whereof I have signed this

